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I'm always quite curious about the "Energy cube" in Transformers, or namely Energon.

Is it really possible to store energy, such as electricity, into such a compact form? safe to distribution, and seems nothing left after being consumed?

ps. Wikipedia has a page for Spark, which is more for transformer's soul. I'm not asking for that yet.

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Arguably by E=mc^2 matter is a compact form of energy in which there is nothing left once it's used up. Good luck releasing all of it though – Richard Tingle Aug 1 '14 at 10:04
@RichardTingle that's a smart answer but... any more controllable approach? – athos Aug 1 '14 at 10:10
A cube of antimatter would do the trick. But it would be hard to isolate from its surroundings. – Tobias Brandt Aug 1 '14 at 10:11
Antimatter would solve your problem up to an energy density of twice the energy of the matter itself. But you can't do any better, if you increase the energy any more you'll also increase the inertia and weight. Unless some particle physicist has some other creative solution. – Alan Rominger Aug 1 '14 at 13:41
up vote 10 down vote accepted

Some energy densities for easily compactified substances:

Purely electric storage:

  • electric field in a capacitor, 0.000 36 MJ/kg
  • electric field in a supercapacitor, up to 0.004 2 MJ/kg
  • 1 T magnetic field has energy density $\frac{1}{2\mu_0}B^2 = 0.4\,\mathrm{MJ/m^3} $, estimate mass for superconducting magnet enclosure to decide where to put this on the list (pretty low)

Chemical storage (atoms are allowed to trade electrons):

Nuclear storage (atoms are allowed to trade nucleons):

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Obligatory xkcd. – Emilio Pisanty Aug 1 '14 at 13:28
@EmilioPisanty Way ahead of you, see link for "uranium" :-) – rob Aug 1 '14 at 13:30
I find it amazing that between uranium and antimatter there is only three orders of magnitude difference – PlasmaHH Aug 1 '14 at 20:31
@PlasmaHH Indeed! Though the difference between a "typical reactor" and a "breeder reactor" is more striking. I left source links because I don't 100% trust all of these numbers; there are lots of subtleties here. – rob Aug 1 '14 at 20:42
@UserLTK I didn't consider any radionuclides because the rate of energy release cannot be modulated or controlled. The fuels, on the other hand, you can store indefinitely and consume at will. – rob 2 hours ago

It is possible to capture positrons (antiparticle of electron) in a magnetically confined plasma - the repulsive forces get very large unless you do something to equalize the charge. The energy density that could be achieved is stunning.

This was the principal plot line behind Dan Brown's "Angels and Demons" - this plasma (made at CERN, that den of mad scientists plotting to destroy the universe) was intended to be released (the power source containing it would become exhausted) underneath the Vatican, destroying the "center of the Evil Church" (the opinion of the perpetrators...). Of course the hero saves the day.

In principle a few grams of antimatter contains as much energy as the fuel tanks of the space shuttle...

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